The hybrid organo-inorganic compounds [Cu 4 (bipy) 4 V 4 O 11 (PO 4 ) 2 ]nH 2 O (n∼5) (1), [Cu 2 (phen) 2 (PO 4 )(H 2 PO 4 ) 2 (VO 2 )·2H 2 O] (2) and [Cu 2 (phen) 2 (O 3 PCH 2 PO 3 )(V 2 O 5 ) (H 2 O)]H 2 O (3) which present different bridging forms of the phosphate/phosphonate group, show different bulk magnetic properties. We herein analyze the magnetic behaviour of these compounds in terms of their structural parameters. We also report a theoretical study for compound (1) assuming four different magnetic exchange pathways between the copper centres present in the tetranuclear unit. For compound (1) the following J values were obtained J 1 =+3.29; J 2 =−0.63; J 3 =−2.23; J 4 =−46.14cm −1 . Compound (2) presents a Curie–Weiss behaviour in the whole range of temperature (3–300K), and compound (3) shows a maximum for the magnetic susceptibility at 64K, typical for antiferromagnetic interactions. These data where fitted using a model previously reported in the literature, assuming two different magnetic exchange pathways between the four copper(II) centres, with J 1 =−30.0 and J 2 =−8.5cm −1 .